The Energy-Filtered Transmission Electron Microscope (EFTEM) is a technique used in transmission electron microscopy that allows only electrons of particular kinetic energies to form an image. It consists of a magnetic prism and optical column that disperses electrons by energy, and an adjustable slit selects a narrow energy range. This enables elemental mapping by imaging with electrons that have undergone an element-specific energy loss.

1. Energy-Filtered Transmission Electron
Microscope (EFTEM)

2.  Energy-filtering transmission electron
microscope (EFTEM), developed about ten
years ago, is now a routine analysis tool in
the characterization of materials.

3.  It is a technique used in Transmission
electron microscopy, in which only electrons
of particular kinetic energies are used to form
the image .
 The ability of an energy-filter to show a two-
dimensional distribution of a specific
element.
 The images at an energy-loss between 100
and 200 eV.

5.  If a very thin sample is illuminated with a
beam of high-energy electrons, then a
majority of the electrons will pass through
the sample but some will interact with the
sample , Scattered elastically or in elastically ,
Inelastic scattering results in both a loss of
energy and a change in momentum

6.  If the electron beam emerging from the
sample is passed through a magnetic prism,
then the flight path of the electrons will vary
depending on their energy.
 It is possible to place an adjustable slit to
allow only electrons with a certain range of
energies through, and reform an image using
these electrons on a detector.
 The energy slit can be adjusted so as to only
allow electrons which have not lost energy to
pass through to form the image.

9.  It consists of two main parts:
 Magnetic prism
 Optical column

11.  In the curved magnetic field, electrons with
different energies are dispersed, obtained at
the end of this part.
 The magnetic prism is the same as in a
parallel electron energy loss spectrometer

12.  An energy range is selected by a slit located
at the dispersion plane.
 In imaging mode, and an energy-filtered
image occurs at the end of the GIF, where a
slow-scan CCD camera is installed for image
recording.

14.  Spatial resolution refers to the size of the
smallest object that can be resolved on the
ground.
 In a digital image, the resolution is limited by
the pixel size, i.e. the smallest resolvable
object cannot be smaller than the pixel size.
 The spatial resolution obtained in an EFTEM
image is influenced by the specific details of
the experiment itself:

15.  When doing EFTEM at high magnifications
elastic contrast that is always present in
EFTEM images may become visible. as th
collection angle.

16.  Energy filtering can be applied for various
problems:
 Zero-loss filtering :
 Electron spectroscopic imaging :

18.  Zero-loss filtering removes the contribution
 of all in-elastically scattered electrons to both
images and diffraction patterns.
 By using only the zero-loss beam, all in
elastically scattered electron are omitted
(reduction of noise).
 That leads to increased contrast and the
resolution in TEM images.

20.  By using electrons with a well-defined energy
loss (ionization edge), elemental distribution
maps can be generated.